Neuronal network analysis during short time transcranial direct current stimulation with permanent EEG measurement in early childhood: a feasibility study

Transcranial direct current stimulation (tDCS) as a non-invasive stimulation is still in the experimental stage for many psychiatric disorders even in adults. The use of tDCS provides an opportunity to influence neural networks and their functional connectivity. How tDCS affects cortical networks and how it influences the functional connectivity of the developing brain is largely unknown. The electroencephalography (EEG) derivation, which has a precise temporal resolution, is well established in the clinical routine in childhood and, in combination with tDCS, it will give us more information about the changes in connectivity during stimulation. Furthermore, objective stress markers should be established for non-invasive stimulation at younger ages. In this study, we investigated how well we can measure connectivity changes under tDCS in children aged 4 to 8 using EEG. The exclusion criterion was epilepsy. Anodal stimulation of the left dorsolateral prefrontal cortex was performed. Throughout the stimulation, EEG and ECG measurements were taken. Heart rate variability was calculated from the ECG lead as a stress marker. The combination of tDCS and EEG was applicable and not associated with increased stress levels. It was shown to be technically feasible and to provide information about changes in connectivity. This may allow a more specific and targeted use of tDCS in the developing brain. It would be convenient to use it in children because it does not require pharmacological intervention, which children can tolerate, unlike, for example, fMRI.